Magnetic field sensors, also known as magnetometers, are widely used in a number of applications including in, for example, compass, security, and military applications, geophysics and space research, biomagnetism and medical applications, and non-destructive testing. Magnetic field sensors are typically based on semiconductor materials (e.g., Hall sensors, semiconductor magnetoresistors, and so forth) and ferromagnetic materials (e.g., ferromagnetic magnetoresistors and flux guides). Other magnetic field sensors utilize optical, resonant, and superconducting properties. Magnetic field sensors may be designed to sense magnetic fields along one or more mutually exclusive axes, typically referred to as the X-axis, Y-axis, and Z-axis.
Increasingly, designers and manufacturers of magnetic field sensors are implementing self-test capability into magnetic field sensors which can be used to test proper operation of the sensors and/or to allow sensor self-calibration. What is absent in some prior art sensors is the ability to perform a true self-test of the magnetic field sensors. That is, currently implemented self-test in some Z-axis magnetic field sensors excludes the interaction between all of the related elements in order to check for sensor functionality and/or for sensitivity calibration. Thus, what is needed is self-test capability for Z-axis magnetic field sensors that includes the interaction between out-of-plane elements and in-plane detectors to enable a more complete and accurate evaluation of a Z-axis magnetic field sensor.